How to Re-Download OS X Mavericks Installer from the OS X Yosemite App Store
In some specific situations, Mac users running OS X Yosemite may wish to re-download the complete installer application of a prior operating system like OS X Mavericks. This is typically something only advanced users would want to do, perhaps for making a bootable installer for the older OS X version, for upgrading a different Mac, or even to downgrade (more on that in a moment), but unless you have a compelling reason to download the prior OS X release installer there is little other reason to do this.